Deformable wheel assembly

ABSTRACT

A locomotion assembly is provided, suitable to be used in a vehicle. The locomotion assembly comprises a frustum-conical structure comprising at least one flexible member having a frustum-conical surface extending between its relatively narrow and wide ends along a frustum-conical axis, the frustum-conical member being reversibly deformable from its biased rounded shape corresponding to a frustum-conical shape in which its side elevation is circular into a deformed frustum-conical shape in which its side elevation is non-circular. The frustum-conical structure may serve for supporting at least one surface-engaging member convertible between a round wheel-like configuration, in which its side elevation is substantially circular, and a deformed configuration, in which its side elevation is non-circular and in which a larger portion of the surface-engaging member is in contact with a movement surface.

FIELD AND BACKGROUND OF THE INVENTION

This invention relates to a locomotion assembly, in particularly alocomotion assembly for a vehicle, of the kind that can assume arounded, wheel-like configuration and a more flattened, belt likeconfiguration.

Locomotion assemblies that comprise members that can assume a wheel-likeconfiguration, on the one hand, and a caterpillar-like configuration, onthe other hand are known. Some examples of such assemblies are describedin U.S. Pat. Nos. 3,698,461, 6,422,576, 7,334,850, 7,557,078; and arealso described in U.S. Pat. Nos. 7,334,850 and 7,547,078, both assignedto the assignee of the present application.

GENERAL DESCRIPTION

The present invention provides a novel locomotion assembly which can beused for propelling a surface vehicle.

According to the invention, the locomotion assembly comprises at leastone, or preferably a pair of flexible members, each having afrustum-conical surface extending between its relatively narrow and wideends along a frustum-conical axis.

A frustum-conically shaped configuration has a flat pattern projection(2D projection), i.e. the surface of said frustum-conical member can beopened/unfolded into a planar topology. A frustum-conical geometry isknown as that defining a frustum-conical surface extending betweenrelatively large and small circular bases on parallel planes, thusdefining a frustum-conical axis. It should be understood that a truegeometric frustum-conical shape having flat pattern projection isfundamentally different from any conoid shaped body having no suchplanar projection in its behavior while being deformed (in response to aforce applied to its surface) from its original state in which it hascircular cross section and its deformed state in which it hasnon-circular (oval-like) cross section. Moreover, this difference ismore essential when dealing with flexible but substantiallynon-stretchable materials, which is the case in locomotion assemblies.Indeed, when such a flexible and non-stretchable element has a pure coneshape or a part thereof (i.e. frustum-conical shape), deformation ofthis element from its original structure results in that the cone bends,while with a similar material composition element having any otherconoid shape (which has no flat 2D projection) such bending would bepractically impossible. A shape having no flat 2D projection provideshigher rigidity on the cost of flexibility, and vice versa for a shapehaving a flat 2D projection such as a frustum-conical shape. A force ofa given profile applied to a pure cone-shape body and a conoid-shapebody would cause significantly high stress at different points at theconoid-shape body than at the pure cone body, thus periodic applicationof stress (as typically happens when rolling as a wheel of a vehicle forexample) would result in significantly higher material fatigue and heatbuildup in the conoid-shape body, as may.

It should be noted that the frustum-conical member used in thelocomotion assembly of the present invention is flexible such that it isreversibly deformable from its biased rounded shape (being truefrustum-conical one) in which its side elevation is circular into a moreflattened shape (deformed frustum-conical shape) in which its sideelevation is non-circular. The frustum-conical member however is rigidin the meaning that it is non-extendable in its circumferentialdimension. Thus, the frustum-conical member is made of non-stretchableflexible sheet.

The paired frustum-conical members are rotatable about a common axiscoinciding with their frustum-conical axes, and arranged in asubstantially symmetric manner. In this connection, it should be notedthat, for the purposes of the present application, a “substantiallysymmetric arrangement” of the frustum-conical members should beinterpreted broader than bilateral or mirror symmetry. The pairedfrustum-conical members are referred to as “substantially symmetricallyidentical” or as arranged in a “substantially symmetric” fashion, in themeaning that they are oppositely oriented with a common axis (they faceeach other either by their wide ends or by their narrow ends), and theyare either identical or have similar geometry, i.e. being parts ofcongruent cones. Thus, the frustum-conical members of a pair have equalconical angles, and may for example have equal geometry (dimensions) attheir wide ends, and the same or different heights (i.e. lengths alongtheir axes) and accordingly the same or different geometry (dimensions)at their narrow ends.

Also, it should be noted that the frustum-conical member may be formedby a single element having a frustum-conical surface or by multipleelements defining together said frustum-conical surface.

The frustum-conical members of a pair are assembled inversely(oppositely oriented), and forces of any type (e.g. driving forces)applied to the surface of one such member to roll in a radius around itsgeometric vertex are balanced by the same forces applied from theopposite member, resulting in that an assembly formed by such pair ofinverted frustum-conical members rolls in a straight line (i.e.perpendicular to the frustum-conical axis). By coupling such assembly ofthe paired frustum-conical members to a wheel would result in the wheelmovement along a line perpendicular to the wheel axis (i.e. a straightline).

The two frustum-conical members of a pair may be arranged in differentways, provided the two members are concentrically arranged andoppositely oriented. In some examples, they are arranged in aspaced-apart relationship along the common axis, for example, such thattheir narrower or wider bases are coinciding (as a ‘back’ to ‘back’ or‘face’ to ‘face’ arrangement). In another example, each of thefrustum-conical members includes a patterned portion of itsfrustum-conical surface formed by an array of slits (receptacles,grooves, cavities or bores) spaced by rigid spikes along itscircumference at the side by which it faces the other member, thusformatting a grid and enabling one frustum-conical member to engage with(penetrates into) the other in conjunction, so there is no contactbetween the walls of the frustum-conical members. In yet anotherexample, two frustum-conical members are configured such that each ofthem is divided into two parts in manner that there is no such regionwhere segments of one frustum-conical member pass into the otherfrustum-conical member, but rather a small part of one member is coupledin a partial flexible manner to a larger part of the other oppositelyoriented member. Generally speaking the configuration of a structureformed by a pair of frustum-conical members is such that an externalcircumferential part of the structure executes coupling between the twooppositely oriented frustum-conical members, via their common axis.

The frustum-conical structure formed by at least one or preferably by apair of the above-described frustum-conical members may serve as asupport structure for supporting at least one surface-engaging member ofthe locomotion assembly. The surface-engaging member is convertiblebetween a round wheel-like configuration, in which its side elevation issubstantially circular, and a deformed configuration, in which its sideelevation is non-circular and in which a larger portion of thesurface-engaging member is in contact with the surface of movement (e.g.ground).

To facilitate understanding, a surface of movement will be referred toherein as ground, but it should be understood that the invention islimited neither to a ground movement of a locomotion assembly nor to amovement along any solid surface.

The surface-engaging member has typically an outer surface by which itcontacts the surface of movement, such that in the deformed state of thesurface-engaging member, said outer surface thereof maintains thesubstantially parallel orientation with respect to the surface ofmovement.

Considering a pair of the frustum-conical support members, theconfiguration may be such that they, by their wide ends, support thesame or separate surface-engaging members. Thus, when thefrustum-conical structure is mounted in the locomotion assembly, each ofthe frustum-conical members, at the wide end of its frustum-conicalsurface, may be is coupled to the surface-engaging member, such that thepaired support members are coupled to the same surface-engaging memberor two different surface-engaging members. The arrangement is such thata bias of each of the frustum-conical members of a pair to move in anon-linear direction (and thus induce the surface engaging member tomove in a non-linear direction) is offset by the other frustum-conicalmember of the pair.

The frustum-conical structure described above may by itself form awheel, namely the wide ends of the frustum-conical members of a pair maypresent a ground-engaging surface of the wheel. In another embodiment, awheel may comprise an inflatable rubber tire defining an enclosedfluid-pressure holding space with a circumferential surface-engagingmember; and a support structure integrally formed in the wheel andcomprising the above-described frustum-conical structure formed by atleast one pair of oppositely oriented frustum-conical support members ofequal conical angles, each defining a frustum-conical surface extendingbetween relatively narrow and wide ends of the support member along afrustum-conical axis, each of the support members being coupled at thewide end of the frustum-conical surface to one side of thesurface-engaging member opposite that of the other, each support memberbeing made from a rigid material and being flexible and biased intorounded shape in which its side elevation is circular and beingreversibly deformable into a more flattened shape in which its sideelevation is non-circular. The deformation of the support structurepermits the reversible deformation of the surface-engaging member from asubstantially circular shape to a deformed shape in which a largerportion of a ground-engaging surface is in contact with a movementsurface.

Thus, the frustum-conical structure of the invention, formed by at leastone or preferably at least one pair of frustum-conical support members,links the surface-engaging member(s) and a vehicle's axle, transferringa force from the vehicle's axle to the surface-engaging member. Theflexible support members are reversibly deformable from their natural,frustum-conical shape (in which they have a substantially circularcross-sectional shape) into a deformed, somewhat flattened shape intandem with the conversion of the surface-engaging member(s) from theround configuration to the deformed non-circular configuration. Throughits flexibility, said linking support structure can translate or linkbetween a circular motion at the axle to a non-circular,caterpillar-like motion of the surface-engaging member in which asegment thereof is in contact with the surface of movement (e.g.ground).

By an embodiment of the invention there is provided a locomotionassembly for a vehicle that comprises a flexible surface-engaging memberand a flexible support structure. The flexible surface-engaging memberhas wheel-like, essentially circular configuration with its outersurface which may be rigid, pliable or flexible. The support structureis configured as described above, comprising at least one pair ofsymmetrically arranged frustum-conical shaped support members definingtogether a common longitudinal axis that is substantially horizontallyoriented. The first wide end of the support member is linked to thesurface-engaging member and the second narrow end is rotationally fixedto an axle of the vehicle to permit rotation about said longitudinalaxis. Said support structure and said surface-engaging member areflexible and reversibly deformable between the wheel-like configurationand a non-circular configuration in which a stretch of saidsurface-engaging member is essentially parallel to the ground and incontact therewith.

In accordance with an embodiment of the invention the locomotionassembly is intrinsically biased to assume a circular configuration. Thelocomotion assembly may, in accordance with an embodiment of theinvention, become deformed to assume a non-circular configuration inresponse to a load on said axle.

In accordance with an embodiment of the invention an actuatingarrangement is provided for forcing the locomotion assembly to assumeone of its configurations. An example of such an actuating arrangementis a pneumatic one in which the gas pressure within an enclosure biasesthe locomotion assembly to assume a wheel-like configuration, while alowering of the gas pressure permits the locomotion assembly to assume anon-circular configuration. Such enclosure, by an embodiment, isannular.

A locomotion assembly according to an embodiment of the inventioncomprises a flexible ground-engaging member having a wheel-like,essentially circular configuration with a ground-engaging surface with afirst rim and a second rim corresponding to a first side and second sideof the locomotion assembly. The locomotion assembly of this embodimentcomprises a flexible support structure with a first support arrangementand a second support arrangement, each having a frustum-conical shapewhen the ground-engaging member has a wheel-like configuration. Each ofthe support arrangements extends between a respective first end and asecond end of narrower diameter, and both define by theirfrustum-conical axes a common longitudinal axis substantiallyhorizontally oriented. The first end of one of the support arrangementsis linked to a first rim of the ground-engaging surface and the firstend of the other is linked to the second rim of the ground-engagingsurface. The support structure and the ground engaging member areflexible and reversibly deformable between the wheel-like configurationin which the support arrangements have the frustum-conical shape and anon-circular configuration in which a stretch of said surface-engagingmember is essentially parallel to the ground and in contact therewithand the support structure has a deformed frustum-conical configuration.

Also in the case of this embodiment, the locomotion assembly may beintrinsically biased to assume a circular configuration. Also, it may bedeformable to assume a non-circular configuration in response to a loadon said axle. Alternatively, or in addition, the locomotion assembly mayalso comprise an actuating arrangement for forcing the locomotionassembly to assume one of its configurations. An example of an actuatingarrangement is a pneumatic one. A pneumatic actuating arrangementtypically comprises an enclosure (usually annular) for compressed gas,wherein the pressure of the gas controls the configuration of thelocomotion assembly. For example, a high gas pressure may bias thelocomotion assembly to assume a wheel-like configuration and a loweringof the gas pressure permits the locomotion assembly to assume anon-circular configuration.

As indicated above, the two frustum-conical support members/arrangementsof the support structure have opposite symmetric orientation. Typically,there support arrangements are linked to an axial hub at their secondends.

By one embodiment of the invention, each of the support arrangementscomprises a plurality of rigid spikes. The rigid spikes may definetogether a mid-portion of the support arrangement linking between firstand second end portions thereof. Typically, the first supportarrangement extends between the first rim of the ground-engaging memberto the second side of the locomotion assembly and the second supportarrangement extends between the second rim of the ground-engaging memberto the first side of the locomotion assembly, the frustum-conical axesof the two support arrangements crossing one another at saidmid-portion.

By an embodiment of the invention, the first portion of each of the twosupport arrangements is integral with the second portion of each of theother of the two support arrangements. The locomotion assembly may thuscomprise a circular, substantially V-shaped groove formed one at eachside of the locomotion assembly. Such groove is defined by a first, moreperipheral wall and a second, more central wall. The first wallconstitutes the first portion of one support arrangement and the secondwall constituting a second portion of the other support arrangement.

By an embodiment of the locomotion assembly, at least one, typicallyboth the first segments of each of the support arrangements is integralwith the ground-engaging member.

By an embodiment of the locomotion assembly the first and secondportions comprise an elastomer.

The locomotion assembly, by an embodiment, comprises rigid spikeslinking the first and the second portions and received in appropriatereceptacles (grooves, cavity or bores) defined in the first and secondportions.

It should be understood that the frustum-conical support structure maybe configured from two or more elements made form any suitable material,iron or polymer for example.

A locomotion assembly, according to another embodiment, comprises aflexible, elastomeric ground-engaging member having wheel-like,essentially circular configuration with a ground-engaging surface with afirst rim and second rim corresponding to a first side and a second sideof the wheel; and a flexible support structure. The latter comprises afirst support arrangement and a second support arrangement. Eachcomprises a first elastomeric portion integral with the ground engagingmember and a second elastomeric portion at second end, and comprising aplurality of rigid spikes defining a mid-portion, each of the spikesbeing tightly received within a receptacle defined in the first andsecond portions. The first support arrangement extends between saidfirst rim to the second side of the locomotion assembly and the secondsupport arrangement extends between said second rim to the first side ofthe locomotion assembly. The two support arrangements have afrustum-conical shape and cross one another at said mid-portion. Thefirst portion of each of the support arrangements is integral with thesecond portion of the other support arrangement. The locomotion assemblyis reversibly deformable between the wheel-like configuration in whichthe support arrangements are frustum-conical and a non-circularconfiguration in which a stretch of said ground-engaging member isessentially parallel to the ground and in contact therewith and thesupport structure has a deformed frustum-conical configuration.

The locomotion assembly of the latter embodiment also typicallycomprises a circular, substantially V-shaped groove formed one at eachside of the locomotion assembly. The groove has a first, more peripheralwall and a second, more central wall. The first wall constitutes thefirst portion of one support arrangement and the second wallconstituting a second portion of the other support arrangement.

By an embodiment of the locomotion assembly, there is confined spacedefined between the ground-engaging member, the first portions and thesecond portions which may or may not be filled with certain media, suchas compressed gas or liquid, in which case the gas pressure controls theconfiguration of the locomotion assembly. Alternatively, the confinedspace may be filled by air from the surroundings in which case theflexibility is defined by the elasticity of the material composition ofthe ground-engaging member.

Also provided by the invention is a vehicle comprising the locomotionassembly of as disclosed above and below.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, embodiments will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings,in which:

FIG. 1A is a perspective view, from one side, of a locomotion assemblyin accordance with an embodiment of the invention.

FIG. 1B is a perspective view of the locomotion assembly of FIG. 2A fromits opposite, side.

FIG. 1C is a cross-section of the locomotion assembly of FIG. 2A. FIGS.2A, 2B and 2C are perspective views and cross-sections corresponding tothose of FIGS. 1A-1C, with the locomotion assembly in a deformed,non-circular configuration.

FIG. 3 shows a locomotion assembly according to an embodiment of theinvention in a deformed configuration with a ground-engaging memberbeing removed for illustrative purposes.

FIGS. 4A and 4B, respectively, are a side and front elevation of alocomotion assembly, in accordance with another embodiment of theinvention.

FIG. 4C is a longitudinal section through lines IV-IV in FIG. 4A.

FIG. 5A is an enlarged view of the section marked V in FIG. 4C.

FIGS. 5B and 5C are isometric cross-sectional views of the sectionmarked V in FIG. 4C.

FIG. 6A is a front elevation of a locomotion assembly, in accordancewith another embodiment of the invention.

FIG. 6B is an isometric view of the locomotion assembly of FIG. 6Ashowing an actuating arrangement, in accordance with an embodiment ofthe invention.

FIG. 6C shows a locomotion assembly with the actuating arrangement beingremoved for illustrative purposes.

FIG. 6D is an isometric cross-section along lines VI-VI in FIG. 6C.

FIGS. 7A-7C illustrate a locomotion assembly, according to anotherembodiment of the invention, wherein FIG. 7A is a longitudinalcross-section, FIG. 7B is an enlarged view of the section marked VII inFIG. 7A and FIG. 7C is an exploded, isometric view of the locomotionassembly.

FIGS. 8A and 8B show a model of a locomotion assembly, in accordancewith an embodiment of the invention, in the respective circular anddeformed configurations.

FIGS. 9A and 9B show a ground-engaging footprint of the tractionassembly in the respective configurations of FIGS. 8A and 8B.

FIGS. 10A and 10B are, respectively, a perspective view and sectionperspective view of a locomotion assembly, in accordance with anembodiment of the invention.

FIGS. 11A-11C are, respectively, a perspective view, a sectionperspective view and longitudinal cross-sectional view of a locomotionassembly, in accordance with another embodiment of the invention.

FIG. 11D is an enlarged section perspective view of a portion of thelocomotion assembly.

FIG. 11E shows a view of the same portion as that of FIG. 11D, withoutthe spikes.

FIGS. 12A and 12B show a locomotion assembly of the kind shown in FIGS.11A-11E, in a circular, wheel-like configuration and in a deformedflattened configuration, respectively.

FIGS. 13A and 13B show a tractor with rear locomotion assembly of thekind shown in FIGS. 12A-12B in the configurations of FIGS. 12A and 12B,respectively.

FIGS. 14A and 14B show yet another example of a wheel structure, inwhich the entire frustum-conical support structure is formed from asuitable resilient material, such as a sheet of steel, thus eliminatinga need for an additional resilient enclosure.

FIGS. 15A and 15B show a further example of the frustum-conicalstructure in which the frustum-conical members of the pair are separatedfrom one another (rather than being engaged) and thus have continuousfrustum-conical surfaces (rather than having patterned portions toengage one another).

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is being made to FIGS. 1A-1C showing a wheel constituting alocomotion assembly 20, in accordance with an embodiment of theinvention, in its circular configuration. The locomotion assembly 20includes a frustum-conical structure 30, which in this example isassociated with a ground-engaging member 22 (constituting asurface-engaging member), and serves as a support structure forsupporting ground-engaging member 22. The ground-engaging member 22 hasan overall structure resembling that of a tractor's tyre. As can beseen, particularly in FIG. 2C, defined below the ground-engaging member22 defines a circumferential tight space 24. This space 24 can beinflated with compressed gas or liquid for controllingresiliency/rigidity. The ground-engaging member 22 has downward facingrims 26 and 26A, which are engaged with end portions of the supportstructure 30, which will be discussed below.

The support structure 30 includes at least one flexible support member34. The member 34 has a frustum-conical surface extending between afirst, relatively wide end 36 and a second narrower end 38, and defininga longitudinal axis A, which in some cases might be substantiallyhorizontally oriented. The support member 34 may be formed by a singlefrustum-conical element, or by multiple support elements definingtogether said frustum-conical surface.

The frustum-conical structure serves as a linking structure fortransferring force from a vehicle's axle to the rotation axis of thelocomotion assembly. In this example, the support member 34, by itsfirst end 36, supports the ground-engaging member 22, and serves as alinking member for transferring force from a vehicle's axle to therotational axis of the ground-engaging member. As shown in the presentexample, the first end 36 is fitted within the circumferential recessdefined by downward-facing rim 26. Radially-extending from the secondnarrower end 38 is an end plate 42 fitted with a cylindrical hub 44which, in use, receives an axle of the vehicle (not shown). Thus, whenin use the locomotion assembly rotates about axis A. The engagement ofthe locomotion assembly to a vehicle's axle may be from each one of thesides of the assembly.

As indicated above, the support structure 30 preferably include at leastone pair of the frustum-conical support members. A secondfrustum-conical support member 50 of the pair is substantiallysymmetrically identical with the first support member 34, namely has anoppositely-oriented frustum-conical shape of the same conical angle andthe same geometry of the wide end thereof, while the same or differentheight and accordingly the same or different geometry of the narrow end.The support members of the pair face each other either by their first(wider) ends or by their second (narrower) ends.

In this example, the support member 50 is mounted over the surfacedefined by its paired support member 34. An external end 60 is fittedinto the groove defined by rim 26A. The first end 36 of the supportmember 34 and the external end 60 of the support member 50 are equallydistanced from axis A. Consequently, in the configuration shown in FIGS.1A-1C, the locomotion assembly behaves in a wheel-like fashion.

The locomotion assembly of this embodiment is self-biased to assume acylindrical configuration with a substantially rounded, side elevation.By way of example, when a force is applied to the frustum-conicalsurface of the support structure (e.g. a load is applied on the axle),the locomotion assembly may assume the deformed configuration, as shownin FIGS. 2A-2C.

FIGS. 2A-2C show the locomotion assembly in the same views as FIGS.1A-1C but in the deformed configuration. As can be seen, a portion 70,which bears onto the ground represented by line 72 (constituting amovement surface), is flattened and essentially parallel to the groundand in contact therewith. In this configuration, the locomotion assemblythus has a larger footprint (as illustrated in FIG. 9B), as compared tothe smaller footprint in the wheel-like configuration (illustrated inFIG. 9A). Therefore, in some respects, in the deformed configuration thelocomotion assembly has a caterpillar-like mode of action but withoutthe pulleys that are needed in caterpillars.

Reference is now made to FIG. 3 showing more specifically the supportstructure 30. The support structure includes oppositely oriented(symmetrically oriented) frustum-conical support members 34 and 50. Ascan be seen, in the deformed state, circumferential end 60 of supportmember 50 and first end 36 of support member 34 are both deformed.

Reference is now made to FIGS. 4A-5C showing a locomotion assemblyaccording to another embodiment of the invention. As can be seen, theexternal end 36 of support member 34 and external end 60 of supportmember 50 are axially slit by slits 80 to improve flexibility of theentire structure.

Resiliency of the support structure 30 may be achieved in a variety ofways. By one embodiment, shown in FIGS. 1-4, this is achieved throughthe use of a rigid though pliable material. In other embodiments, thismay be achieved through different solutions. One example is end slits 80of the kind shown in FIGS. 5A-5C. Examples of other solutions areconstruction of each of the support members from several segments,articulated to one another at or about the second end. One othersolution is also disclosed below. The manner of achieving such astructure is within the reach of a person skilled in the art.

Reference is now being made to FIGS. 6A-6D which show a locomotionassembly 90, according to another embodiment of the invention. In thiscase, rather than being a tyre-type ground-engaging member as inpreviously described embodiments, in this embodiment the ground-engagingmember 100 is integrally formed with the support structure 102. Theresiliency is imparted, among others, by the structure of theground-engaging member, which is formed having a plurality of slits 104extending across the ground-engaging member 100 and dividing it into aplurality of segments 106. This embodiment includes also an actuatingmember 120 which, in this exemplary case, is an inflatable, torus-shapedhollow body, which bears against an inside surface 124 of the supportstructure 102. When inflated, it imparts rigidity and hence a circularshape; and when deflated, the traction assembly can assume a deformed,flattened configuration. Actuating member 120 may by other embodimentsbe disposed at the opposite side of the wheel. By other embodiments itmay include an arrangement with parts on opposite side of the wheel.

Another embodiment of a locomotion assembly is shown in FIGS. 7A-7C. Inthis case, a ground-engaging member 130 is a separately formed body thatis made to be flexible by slits 132 formed in the sides ofground-engaging member 130. A support structure 134 includes a pair ofsymmetrically (oppositely) oriented frustum-conical support members 136and 140, and an end member 138 being an auxiliary support member. Thesupport members 136 and 140 have the same geometry at their first wideends (external ends of the support structure) and equal conical angle,but in this example they have different lengths and accordinglydifferent dimensions at their second narrower ends. As also shown in thefigures, the wider ends of the support members by which they are tosupport the ground-engaging member define planar external surfaces ofthe support structure (planar bases of the support members). Theauxiliary support member 138 also has a frustum-conical shape orientedsimilar to that of support member 136. As can best be seen in FIG. 7Cthe different components are assembled together and may be fitted withone another through one or more of pressure fitting, welding to oneanother, through knits, screws and many others.

Exemplary models of the locomotion assembly are shown in FIG. 8A in itscircular configuration and in FIG. 8B in its deformed configuration. Thecorresponding footprints of these model embodiments are shown in FIGS.9A and 9B, respectively.

Reference is now made to FIGS. 10A and 10B showing a locomotion assembly200 including a flexible ground-engaging member 202 with a groundengaging surface 204, and a flexible support structure 220. Thelocomotion assembly 200 has a wheel-like, essentially circularconfiguration as shown and has the flexibility to assume a flattened,non-circular configuration, with the ground-engaging surface 204 beingin contact with the ground throughout an extended segment thereof (aswill be explained below). The ground-engaging member 202 has first andsecond rims 206 and 208 at a first side 210 and second side 212 of thelocomotion assembly, respectively.

The ground-engaging member 202 is supported by the flexible supportstructure 220 which includes two support arrangements that are bothfrustum-conical members made of a number of cooperating components thatjointly define two, oppositely oriented frustum-conical surfaces asoutlined by lines 216 and 218. These frustum-conical surfaces extendfrom their first ends at rims 206 and 208 to their second, narrowerdiameter ends 222 and 224. It should be noted that the frustum-conicalarrangements have a true frustum-conical shape only in the circular,wheel-like configuration and are shifted into their deformedfrustum-conical shape once the traction assembly assumes a non-circularconfiguration.

Each support arrangement includes a first portion 226 coupled to(integral with) the ground-engaging member 202, a second portion 228 anda mid-portion defined by a plurality of spikes 230. As can be seen, themid-portions of the two support arrangements cross one another with theplurality of spikes 230, forming an interlacing arrangement. Further, ascan also be seen, the first portion 226 and the second portion 228 are,in this specific embodiment, coupled to (integral with) one another.

As can further be seen from FIGS. 10A and 10B, formed at each of sides210 and 212 are respective V-shaped circular grooves 232 and 234, eachwith walls that are defined by first portions 226 and second, integralportion 228 (of the other support arrangement).

The locomotion assembly of this embodiment is integrally formed with arigid hub 252 for linking to a vehicle's axle.

In this specific embodiment, the entire structure is made of metal. Theground-engaging member is comprised of individual segments 240,separated from one another by cuts 242. This ensures an overallflexibility of the ground-engaging member 202. The interlacingarrangement of the two support members/arrangements imparts overallability of radial compression; and accordingly, the ability of theentire locomotion assembly to assume a flattened, non-circular shape,with an extended portion of the ground-engaging surface 204 touching theground and providing a more extensive locomotion surface.

By some embodiments, a tube or another resilient enclosure (not shown)may be included in either one or both of spaces 247 and 249 definedwithin the locomotion assembly.

Reference is now being made to FIGS. 11A-11E showing a locomotionassembly 300 according to another embodiment of the invention. Elementshaving the same function as in locomotion assembly 200 of FIGS. 10A and10B are given the same reference numerals shifted by one hundred.

The main difference resides in that the locomotion assembly is made ofan elastomeric material, such as rubber, for example of the kindroutinely used in wheels. However, other types of materials may be usedas well.

At ends 322 and 324 of the support arrangements, there are annularshoulders 360 and 362 for fitting over a hub (not shown) and representedby dotted lines 364 in FIG. 11C. Consequently, a circumferentialenclosure 366 is formed, defined by the ground-engaging member 302,first and second portions 326 and 328 and between the hub. The enclosure366 may contain compressed gas, e.g. compressed air, and the pressurecontrols the overall configuration. At high pressure, the locomotionassembly will assume a circular, wheel-like configuration. Once thepressure is reduced, the wheel structure can compress and assume aflattened, non-circular configuration with more extensive locomotionsurface.

FIG. 11D shows a large section of the traction assembly with the spikes330, each received within a cavity 370, formed within first portion 326;and bore 372, formed within second portion 328. As can be seen in FIG.11E, showing the same view with the spikes removed, there is a pluralityof openings 374 at end 324, through which the spikes can be inserted topass through bore 372 and to be received also within cavity 370. Thespikes provide a functional link defining first portion 326 and secondportion 328 as belonging to one functional support arrangement. Thespikes provide the rigidity to the support structure while theelastomeric portions provide the flexibility.

The locomotion assembly of the kind shown in FIGS. 11A-11E is shown inFIGS. 12A and 12B in the circular, wheel-like configuration and in adeformed, flattened configuration, respectively. A tractor with such awheel in the same respective configurations is shown in FIGS. 13A and13B.

The frustum-conical structure of the locomotion assembly of theinvention may be configured from two or more elements made form anysuitable material, iron or polymer for example, provided that thisconfiguration defines frustum-conical geometry as described above.

Some of the above-described examples refer to the wheel structureutilizing a tube or another resilient enclosure. It should be understoodthat the invention is not limited to this specific implementation of thelocomotion assembly. For example, FIGS. 14A and 14B illustrate a wheelstructure which similar to that of FIGS. 10-11 utilizes engagingfrustum-conical members, but in which, instead of using the tubular orthe like resilient enclosure, the entire frustum-conical supportstructure 420 is formed from a suitable material, such as a sheet ofsteel.

It should be understood that using the frustum-conical structure formedby at least one frustum-conical member or preferably at least a pair ofoppositely (substantially symmetrically) oriented frustum-conicalsupport members, provides for transferring a force from the vehicle'saxle to the surface engaging member via the frustum-conical supportmembers. There are several ways for implementing a force transfermechanism within the locomotion assembly.

In some of the embodiments described above, the support structure isformed by two frustum-conical support members, one being larger andactually providing the main support for the ground-engaging member andthe other being smaller (shorter) and acting to induce the supportstructure to move in a linear direction, which otherwise (if formed bythe single frustum-conical support member) would move in a radialdirection, which is natural direction of rolling for a frustum-conicalstructure. In other words, the support structure is configured such thata bias of each of the support members of a pair to induce the surfaceengaging member to move in a non-linear direction is offset by the othersupport member of the pair.

In the above-described embodiments of FIGS. 10-11 and 14, the twofrustum-conical support members are arranged in a so-called “crossing”fashion due to a gripping pattern (spikes) at the frustum-conicalsurfaces of the support members. Alternatively, the support structuremay have no gripping pattern enabling engagement or crossing between thefrustum-conical support members, but rather the frustum-conical membersof the pair may be separate elements, e.g. spaced-apart from each other.This is exemplified in FIGS. 15A and 15B showing a frustum-conicalstructure 520 formed by a pair of oppositely oriented spatiallyseparated members, having continuous frustum-conical surfaces. It shouldbe understood that the support structures of FIGS. 14A-14B and 15A-15Bmay be embedded within an elastomeric matrix to form an inflatable wheelthat can be fitted onto existing wheel drums.

The two frustum-conical support members of a pair may thus be eithercrossing (engaging) one another or separated, and may face each other bytheir identical wide ends or by their narrow ends (identical or not).For example, two frustum-conical members may be configured such thateach of them is divided into two parts in a manner that there is no suchregion where segments of one frustum-conical member pass into the otherfrustum-conical member, but rather a small part of one member is coupledin a partial flexible manner to a larger part of the other oppositelyoriented member. Generally speaking the configuration of thefrustum-conical structure is such that an external circumferential partof the structure, which may be coupled (directly or not) to thesurface-engaging member, executes coupling between the two oppositelyoriented frustum-conical members, via their common axis, due to couplingbetween the other part of the structure to the vehicle's axle.

Those skilled in the art will readily appreciate that variousmodifications and changes can be applied to the embodiments of theinvention as hereinbefore described without departing from its scopedefined in and by the appended claims.

1-41. (canceled)
 42. A locomotion assembly for a land vehicle, thelocomotion assembly comprising a flexible, elastomeric ground-engagingmember having wheel-like, essentially circular configuration with aground-engaging surface with first and second circumferential sidescorresponding to first and second sides of the locomotion assembly,wherein the first and second sides of the locomotion assembly compriserespectively first and second circular, substantially V-shaped, groovesarranged with opposite symmetric orientation with respect to a rotationaxis of the locomotion assembly, providing radial compression of thelocomotion assembly by reversible deformation of the first and secondgrooves, thereby permitting reversible deformation of theground-engaging member from a substantially circular shape to a deformedshape in which a larger portion of the ground-engaging surface is incontact with a movement surface, such that the deformed shape of theground-engaging member provides a larger footprint of the locomotionassembly.
 43. The locomotion assembly of claim 42, wherein each of theV-shaped grooves has first and second frustum conical walls.
 44. Thelocomotion assembly of claim 43, wherein said first and second frustumconical walls are concentrically arranged and oppositely oriented withrespect to the rotation axis of the locomotion assembly, and a wider endof the first frustum conical wall is attached to a narrower end of thesecond frustum conical wall.
 45. The locomotion assembly of claim 43,comprising a pair of frustum-conical members integrally formed and beingcoupled to said ground-engaging member, each of the frustum-conicalmembers of the pair extending between its relatively narrow and itsrelatively wide end along a common frustum-conical axis, being therotation axis of the locomotion assembly, and being rotatable about saidaxis, the frustum-conical members of the pair being symmetricallyoriented and jointly supporting said ground-engaging member at theirwide ends, thereby defining said first and second frustum conical wallsof the first and second circular, substantially V-shaped, grooves of theopposite symmetric orientation.
 46. The locomotion assembly of claim 43,wherein the first and second walls of the groove are defined by surfacesof first and second frustum-conical members of a pair.
 47. Thelocomotion assembly of claim 44, wherein the first and second walls ofthe groove are defined by surfaces of first and second frustum-conicalmembers of a pair.
 48. The locomotion assembly of claim 46, wherein eachof the frustum-conical members of the pair is coupled at the wide endthereof to one side of the ground-engaging member opposite that of theother.
 49. The locomotion assembly of claim 47, wherein each of thefrustum-conical members of the pair is coupled at the wide end thereofto one side of the ground-engaging member opposite that of the other.50. The locomotion assembly of claim 46, wherein the frustum-conicalmembers of the pair are made from a rigid material and are flexible andbiased into rounded shape in which their side elevation is circular andare reversibly deformable into a more flattened shape in which theirside elevation is non-circular.
 51. The locomotion assembly of claim 47,wherein the frustum-conical members of the pair are made from a rigidmaterial and are flexible and biased into rounded shape in which theirside elevation is circular and are reversibly deformable into a moreflattened shape in which their side elevation is non-circular.
 52. Thelocomotion assembly of claim 46, wherein the frustum-conical members ofthe pair comprise an array of slits forming a grid enabling engagementbetween the frustum-conical members of said pair.
 53. The locomotionassembly of claim 47, wherein the frustum-conical members of the paircomprise an array of slits forming a grid enabling engagement betweenthe frustum-conical members of said pair.
 54. The locomotion assembly ofclaim 46, wherein each of the frustum-conical members of the paircomprises a plurality of rigid spikes.
 55. The locomotion assembly ofclaim 47, wherein each of the frustum-conical members of the paircomprises a plurality of rigid spikes.
 56. The locomotion assembly ofclaim 42, comprising an actuating arrangement for forcing theground-engaging member to assume one of its configurations.
 57. Thelocomotion assembly of claim 56, wherein the actuating arrangement ispneumatic.
 58. The locomotion assembly of claim 56, comprising anenclosure for compressed gas, wherein the pressure of the gas controlsthe configuration of the locomotion assembly.
 59. The locomotionassembly of claim 58, wherein a high gas pressure biases the locomotionassembly to assume a wheel-like configuration and a lowering of the gaspressure permits the locomotion assembly to assume a non-circularconfiguration.
 60. The locomotion assembly of claim 46, wherein thefirst frustum-conical member of the pair extends between the first sideof the ground-engaging member to the second side of the locomotionassembly and the second frustum-conical member of the pair extendsbetween the second side of the ground-engaging member to the first sideof the locomotion assembly, the two frustum-conical members of the paircrossing one another at a mid-portion defining an apex portion of theV-shaped groove.
 61. A locomotion assembly for a land vehicle, thelocomotion assembly comprising a flexible, elastomeric ground-engagingmember having wheel-like, essentially circular configuration with aground-engaging surface with first and second circumferential sidescorresponding to first and second sides of the locomotion assembly,wherein the first and second sides of the locomotion assembly compriserespectively first and second circular, substantially V-shaped, groovesarranged with opposite symmetric orientation with respect to a rotationaxis of the locomotion assembly, each of the grooves has first andsecond frustum conical walls, and is configured such that the first andsecond frustum conical walls are concentrically arranged and oppositelyoriented with respect to the rotation axis of the locomotion assembly,and a wider end of the first frustum conical wall is attached to anarrower end of the second frustum conical wall, thereby providingradial compression of the locomotion assembly by reversible deformationof the first and second grooves, and permitting reversible deformationof the ground-engaging member from a substantially circular shape to adeformed shape in which a larger portion of the ground-engaging surfaceis in contact with a movement surface, such that the deformed shape ofthe ground-engaging member provides a larger footprint of the locomotionassembly.
 62. A wheel for a land vehicle comprising an inflatable rubbertire defining an enclosed fluid-pressure holding space with acircumferential ground-engaging member, having a ground-engaging surfacewith first and second sides corresponding to first and second sides ofthe wheel, wherein the first and second sides of the wheel compriserespectively first and second circular, substantially V-shaped, groovesarranged with opposite symmetric orientation with respect to a wheelrotation axis, providing radial compression of the wheel by reversibledeformation of the first and second grooves, thereby permittingreversible deformation of the ground-engaging member from asubstantially circular shape to a deformed shape in which a largerportion of the ground-engaging surface is in contact with a movementsurface.